1. Field of the Invention
The present invention relates to a lens barrel having means for removing deleterious light in an optical path of a photographic optical system.
2. Related Art Statement
Conventionally, the structure for removing light beams other than those reaching a film exposing plane in an optical path of a photographic optical system incorporated in a lens barrel has been widely known in the art.
For example, Laid-open Japanese Utility Model No. 63-160520 discloses a structure for moving a flare diaphragm forwards and rearwards along the direction of the optical axis with a zoom cam arranged in a zoom lens barrel.
Also, Laid-open Japanese Pat. Application No. 60-194414 discloses a structure which includes a flare diaphragm of a variable diameter so that the diameter of the flare diaphragm is changed on a plane perpendicular to the optical axis.
However, the structure disclosed in the above-mentioned Laid-open Japanese Utility Model No. 63-160520 has a problem in that deleterious light flux cannot be effectively cut since the flare diaphragm moves forwards and backwards along the optical axis.
The structure disclosed in the above-mentioned Laid-open Japanese Pat. Application No. 60-194414, in turn, has a problem in that the size of the entire lens barrel becomes larger because of a large space required to accommodate the flare diaphragm.